Gestational diabetes mellitus(GDM) is defined as carbohydrate intolerance of variable severity with onset or first recognition during pregnancy. Since GDM is usually not diagnosed until 24 weeks' gestation or later its duration is not well defined. Thus, it is an heterogenous disease including some patients with pregestational diabetes and others with true gestational hyperglycemia. An analogous situation is type II diabetes mellitus (DM) where the duration of hyperglycemia at time of the diagnosis is unknown.